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  <title>去除字符串首尾处的空白字符（或者其他字符）</title>

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</div><hr /><div id="function.trim" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">trim</h1> 
  <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">trim</span> &mdash; <span class="dc-title">去除字符串首尾处的空白字符（或者其他字符）</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.trim-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type">string</span> <span class="methodname"><strong>trim</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$str</code></span>
   [, <span class="methodparam"><span class="type">string</span> <code class="parameter">$charlist</code></span>
  ] )</div>

  <p class="para rdfs-comment">
   此函数返回字符串 <em><code class="parameter">str</code></em> 去除首尾空白字符后的结果。如果不指定第二个参数，<span class="function"><strong>trim()</strong></span> 将去除这些字符：
   
   <ul class="itemizedlist">
    <li class="listitem">
     <span class="simpara">
      &quot; &quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>32</em> 
      (<em>0x20</em>))，普通空格符。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      &quot;\t&quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>9</em> 
      (<em>0x09</em>))，制表符。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      &quot;\n&quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>10</em> 
      (<em>0x0A</em>))，换行符。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      &quot;\r&quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>13</em> 
      (<em>0x0D</em>))，回车符。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      &quot;\0&quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>0</em> 
      (<em>0x00</em>))，空字节符。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara"> 
      &quot;\x0B&quot; (<acronym title="American Standard Code for Information Interchange">ASCII</acronym> <em>11</em> 
      (<em>0x0B</em>))，垂直制表符。
     </span>
    </li>
   </ul>
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.trim-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">str</code></em></dt>

     <dd>

      <p class="para">
       待处理的<span class="type"><span class="type 字符串">字符串</span></span>。
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">charlist</code></em></dt>

     <dd>

      <p class="para">
      可选参数，过滤字符也可由 <em><code class="parameter">charlist</code></em> 参数指定。一般要列出所有希望过滤的字符，也可以使用 “<em>..</em>” 列出一个字符范围。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.trim-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   过滤后的字符串。
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.trim-changelog">
  <h3 class="title">更新日志</h3>
  <p class="para">
   <table class="doctable informaltable">
    
     <thead>
      <tr>
       <th>版本</th>
       <th>说明</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td>4.1.0</td>
       <td>
        新增可选的 <em><code class="parameter">charlist</code></em> 参数。
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-function.trim-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4823">
    <p><strong>Example #1 <span class="function"><strong>trim()</strong></span> 使用范例</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$text&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"\t\tThese&nbsp;are&nbsp;a&nbsp;few&nbsp;words&nbsp;:)&nbsp;...&nbsp;&nbsp;"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$binary&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"\x09Example&nbsp;string\x0A"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$hello&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"Hello&nbsp;World"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$text</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$binary</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$hello</span><span style="color: #007700">);<br /><br />print&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$trimmed&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$text</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$trimmed</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$trimmed&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$text</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"&nbsp;\t."</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$trimmed</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$trimmed&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$hello</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"Hdle"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$trimmed</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;清除&nbsp;$binary&nbsp;首位的&nbsp;ASCII&nbsp;控制字符<br />//&nbsp;（包括&nbsp;0-31）<br /></span><span style="color: #0000BB">$clean&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$binary</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"\x00..\x1F"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$clean</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
string(32) &quot;        These are a few words :) ...  &quot;
string(16) &quot;    Example string
&quot;
string(11) &quot;Hello World&quot;

string(28) &quot;These are a few words :) ...&quot;
string(24) &quot;These are a few words :)&quot;
string(5) &quot;o Wor&quot;
string(14) &quot;Example string&quot;
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-4824">
    <p><strong>Example #2 使用 <span class="function"><strong>trim()</strong></span> 清理数组值</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">trim_value</span><span style="color: #007700">(&amp;</span><span style="color: #0000BB">$value</span><span style="color: #007700">)&nbsp;<br />{&nbsp;<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$value&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$value</span><span style="color: #007700">);&nbsp;<br />}<br /><br /></span><span style="color: #0000BB">$fruit&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">'apple'</span><span style="color: #007700">,</span><span style="color: #DD0000">'banana&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'&nbsp;cranberry&nbsp;'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruit</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">array_walk</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruit</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'trim_value'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruit</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
array(3) {
  [0]=&gt;
  string(5) &quot;apple&quot;
  [1]=&gt;
  string(7) &quot;banana &quot;
  [2]=&gt;
  string(11) &quot; cranberry &quot;
}
array(3) {
  [0]=&gt;
  string(5) &quot;apple&quot;
  [1]=&gt;
  string(6) &quot;banana&quot;
  [2]=&gt;
  string(9) &quot;cranberry&quot;
}

</pre></div>
    </div>
   </div>
  </p>
 </div>



 <div class="refsect1 notes" id="refsect1-function.trim-notes">
  <h3 class="title">注释</h3>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <strong>Possible gotcha: removing middle characters</strong><br />
   <p class="para">
    Because <span class="function"><strong>trim()</strong></span> trims characters from the beginning and end of
    a <span class="type"><a href="language.types.string.html" class="type string">string</a></span>, it may be confusing when characters are (or are not) removed from
    the middle. <em>trim(&#039;abc&#039;, &#039;bad&#039;)</em> removes both &#039;a&#039; and &#039;b&#039; because it
    trims &#039;a&#039; thus moving &#039;b&#039; to the beginning to also be trimmed. So, this is why it &quot;works&quot;
    whereas <em>trim(&#039;abc&#039;, &#039;b&#039;)</em> seemingly does not.
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.trim-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.ltrim.html" class="function" rel="rdfs-seeAlso">ltrim()</a> - 删除字符串开头的空白字符（或其他字符）</span></li>
    <li class="member"><span class="function"><a href="function.rtrim.html" class="function" rel="rdfs-seeAlso">rtrim()</a> - 删除字符串末端的空白字符（或者其他字符）</span></li>
    <li class="member"><span class="function"><a href="function.str-replace.html" class="function" rel="rdfs-seeAlso">str_replace()</a> - 子字符串替换</span></li>
   </ul>
  </p>
 </div>

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